1. Field of the Invention
The present invention relates to a method for growing Group III nitride; more particularly, the present invention relates to a method for growing Group III nitride which is applicable to the light emitting diode.
2. Description of the Related Art
In recent years, the Group III nitride is gaining prominence in the global semiconductor industry, due to the direct bandgap, excellent radiation resistance, thermal conductance, strong bonding force, etc. thereof. The Group III nitride finds its application in the blue, green, and ultraviolet light emitting elements as well as high power, high frequency or high temperature element. Presently, the Group III nitride with widespread application includes Aluminum nitride (AlN), gallium nitride (GaN), aluminum gallium nitride (AlGaN), indium nitride (InN) and the mixed crystallization of them.
Conventionally, the majority of the semiconductor material applied in the industry comes in the form of bulk material. Alas, the cost of production for the large monocrystalline Group III nitride is too high, so the conventional way to manufacture electronic elements containing Group III nitride involves growing a film of Group III nitride via heteroepitaxy and then using the film as the substrate for the growth of other material. The common substrate for the initial heteroepitaxy includes sapphire, silicon carbide (SiC) and silicon; however the lattice constant and the thermal expansion coefficient of the Group III nitride and the aforementioned substrate materials usually differ significantly, so various defects may be induced in the subsequent epitaxy growth, for instance, the threading dislocations, stacking faults, etc. These defects may cause the indirect recombination center to introduce unwanted energy levels in the bandgap, thus reducing the life of the charge carrier. Besides the imperfection may increase the threshold voltage and reduce the thermal conductivity of the electronic elements. So, it is desirable to bring down the imperfection density of the Group III nitride induced during the heteroepitaxy growth in order to achieve higher luminous efficiency.
There are various means to reduce the imperfection density; one of the means is the epitaxial lateral overgrowth (ELOG). The ELOG reduces the dislocation density of the Group III nitride by growing the Group III nitride on the micro-stripe patterned epitaxial substrate to form a uniform emissive layer. However, different pattern will produce significantly different results with respect to the fabrication process and the subsequent crystal growth. As the result, the present invention aims to design a pattern to minimize the dislocation density of the Group III nitride.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.